New and emerging managers are strongly discouraged from signing side letters. They are complicated to administer, and changing regulations require that you share them with all other limited partners in the US. This creates challenging situations where all limited partners will request the same "perks."

The best solution is to encourage limited partners to invest is to raise the minimum between closings. Then, you can informally offer first look at co-investment and follow-on opportunities. Do not put anything specific in writing.